About a month ago, we had a new wall oven installed - it’s a dual combo with convection microwave, which died, and we replaced with the equivalent/newer model. Since then, I’ve burned almost everything I’ve made in the oven other than meat (where I use a probe thermometer). So today I did an experiment, and I’m sharing here in case anyone has thoughts/comments about other things to try before I call the appliance store.
Set-up: I put a cast-iron skillet on the bottom rack and placed the probe for my Thermoworks DOT in the skillet (as recommended by this source). I hung the dial oven thermometer above so it was basically in the center of the oven. I turned the oven light on and left it on through this entire experiment.
I closed the door - which stayed closed throughout! - and set the oven to preheat to 350F. Once it preheated, I recorded the temperature readings on both the probe and dial thermometers every 5 minutes for an hour, then every 10 minutes to 90 minutes total.
The results surprised me… they were all over the place!
Conclusions:
Probe always tracked hotter than dial, or dial always tracked low. I’m inclined to think it is the latter, because Thermoworks makes good products and I did buy a cheapo dial thermometer. However, I was not expecting this much difference… the readings ranged from 9 degrees different to 50 degrees different, with an average of 25.
The range of temps is normal. An oven will heat, then stop heating for a while, then kick back on when the temp drops. It’s not a precise continuous heat. I don’t know which thermometer is more accurate, but the average of both sets of numbers looks close to 350, maybe a touch high.
As for burning everything, would you say things get too dark on the bottom, on the top, or just overall cook faster than before? If overall, it could be a stronger convection fan than you’re used to. Every oven bakes a little differently.
would you say things get too dark on the bottom, on the top, or just overall cook faster than before?
They cook faster but also get too dark. For example, I make granola (the same recipe) every week. I make one batch and split it evenly between two baking sheets, a matched set and both lined with parchment. I rotate them (upper/lower rack) halfway through the baking time. Since the new oven went in, whichever tray finishes on the upper rack is extra toasty even if I pull it out at 50 minutes instead of 60.
it could be a stronger convection fan
Would the convection fan kick on when I’m baking just on regular Bake, not with convection? (I’ve never used the convection function, either on the previous oven or the new one.)
To @HappyOnion and @BierMonk ’s comments about not using the CI skillet - I hadn’t fully considered the effect of the heat absorption it would have… this is what I get for ~blindly following instructions I found online. If I have time tomorrow, I’ll repeat with the probe just hanging out near the dial thermometer.
I don’t fully understand our gas oven bought a few years ago, but even when we are using “bake” and not “convect bake” the fan is often on. This does mean I don’t have to switch or rotate pans when roasting/baking with more than one, so I see it as an advantage in some way. On the other hand it usually runs “slow” so we add a few minutes usually. When baking, I always use a insta pen thermometer so I know when to pull it.
I made lasagna tonight… the dial thermometer (mid-oven) matched the setting every time I looked, but it must have been still too hot because the bottom layer of noodles was a little blackened. I think @Babette’s recommendation to drop the temperature by 25 degrees and check at 90% of the baking time is probably my best path forward.
My GE gas stove routinely undercooks everything. I have 2 dial thermometers hanging inside, one on the right side of the oven and one on the left. I see similar hi/lo fluctuations throughout the heating cycle to what you’re seeing. The 2 thermometers don’t agree with each other (they’re different brands), but I’ve also discovered, by swapping them from side to side, that the gas flame on one side of my oven is hotter than the other. (Overall, the oven temp is still lower than the set temp.) Now I just set the temp about 20°F higher than recommended and things cook pretty close to what I’m expecting.
It’s a new oven right? They should be able to fix the calibration or replace it. Did you look online to see if it’s a common issue or a lemon problem?
I have a calibration issue with my countertop oven, but I hadn’t used it for too long after I acquired it to have it replaced. BUT it’s a 25 degree constant only on regular bake (not convection) so I adjust for it — and often leave the thermometer inside.
It didn’t seem to be a known lemon issue with this model, all the Bosch models had low-4 star ratings and a smattering of complaints, as one often finds online. We had to stick with Bosch or find a carpenter and wait longer.
And yeah, I need to call for service but haven’t had a chance!
I think 
